JPH0360302B2 - - Google Patents

Description

[Detailed description of the invention]

I. BACKGROUND TECHNICAL FIELD OF THE INVENTION The present invention relates to a method and apparatus for producing an annular thermoplastic resin film having a roughened inner surface. Prior Art Soft vinyl chloride resin is widely used as a resin for medical devices such as blood bags, infusion bags, and dialysate bags due to its excellent processability, physiological stability, transparency, and low price. There is. However, with medical devices made of soft vinyl chloride resin, a so-called blocking phenomenon (adhesion phenomenon between materials that occurs at temperatures below the melting point of the materials) occurs between the inner surfaces of the medical devices, making it difficult to open the medical device. , drugs inside medical equipment,
There were some inconveniences when filling with blood, etc. As a method for preventing blocking in soft vinyl chloride films, for example, in processing soft vinyl chloride resin films, embossing is applied to the surface of the roll attached to the back-up roll attached to the sheet take-up machine, and embossing is applied to one side of the sheet. There is a way to transfer it. however,
This method requires an expensive embossing roll, and the rough surface becomes smooth after long-term use, making it impossible to form a uniform rough surface over a long period of time. On the other hand, in the inflation molding method, thermoplastic resin is generally extruded into a pipe shape by extrusion molding, and while the temperature of the resin is maintained above its softening point, air is blown into the inside of the resin to form the pipe shape. This is a method in which an object is formed into a film with the desired dimensions, which is then rapidly cooled to below the softening point to solidify it, which is then folded in half with pinch rolls and then wound up one after another with a take-up roll. be.
Inflation-molded sheets generally have mirror surfaces on both the inner and outer surfaces, and when pinched with pinch rolls, blocking occurs between the inner surfaces. As a method to prevent such blocking, a method has been proposed to cool the mandrel part within the die (Japanese Patent Laid-Open Nos. 55-42802 and 50-55672).
However, when molding thermoplastic resins, especially soft vinyl chloride resins, by the inflation molding method using dies with these structures,
Both the inner and outer surfaces are smooth, but it is not possible to form a uniformly rough surface on the inner surface, and even if it is possible to form a uniform rough surface to some extent, it is not possible to form a sufficiently rough surface to prevent blocking due to contact between the inner surfaces. Nakatsuta. OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a novel method and apparatus for producing an annular thermoplastic resin film with a roughened inner surface. Still another object of the present invention is to provide a method and apparatus for manufacturing a sheet for a medical device made of soft vinyl chloride resin, which prevents blocking between inner surfaces. Specific configuration of the invention These objects are constituted by a mandrel and an outer die ring surrounding the mandrel,
A molten thermoplastic resin is flowed into the resin passage of a die equipped with an annular resin passage, and a mandrel that communicates with the resin passage is not more than 30 mm in the axial direction from the lower end of the resin discharge port of the die, at least at a surface facing the resin passage. The surface temperature of the outer die ring is 5
The molten thermoplastic resin is discharged in a ring shape from the resin discharge port at a temperature of ~60°C, and air is retained inside the discharged resin to form a ring-shaped thermoplastic resin film. This is achieved by a method for manufacturing an annular thermoplastic resin film with a roughened inner surface, which is characterized by forming a roughened surface having uniform fine irregularities on the inner surface. Further, the present invention provides a temperature difference between the mandrel and the outer die ring of 10 to 50°C, more preferably 15 to 35°C.
This is a manufacturing method in which the temperature is ℃. The above objects also provide a die including a mandrel, an outer die ring surrounding the mandrel, an annular resin passage formed between the mandrel and the outer die ring, and a resin discharge port communicating with the resin passage. A cooling means for making the temperature of at least the surface of the mandrel of the die facing the resin passage lower than the temperature of the surface of the outer die ring facing the resin passage. This can also be achieved by an apparatus for manufacturing an annular thermoplastic resin film with a roughened inner surface, characterized in that the mandrel is provided at a portion of the mandrel that does not exceed 30 mm in the axial direction from the resin discharge port to the resin passage side. . The present invention also provides a manufacturing apparatus in which the cooling means flows a cooling medium through a cooling medium passage formed in an annular shape at least near the outer surface of the mandrel along the resin discharge port. Further, the present invention is a manufacturing apparatus in which the cooling medium passage is formed near the outer surface of the mandrel, which has the same surface as the resin discharge port. Furthermore, the present invention is a manufacturing apparatus in which the cooling medium passage is formed near the surface of the mandrel that protrudes from the outer surface of the resin discharge port.
The present invention also provides a manufacturing apparatus in which a cooling medium passage is formed within a mandrel protruding from the outer surface of the resin discharge port and at a position substantially flush with the outer surface of the outer die ring. DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described in more detail with reference to the drawings. That is, as shown in FIG. 1, an outer die ring 2 for adjusting thickness unevenness is fitted around the outer periphery of a circular mandrel 1, so that an annular resin passage 3 is formed in the gap between the two. 1
In a die 5 having an air outlet 4 in the center thereof, a mandrel 1 is provided near the outer surface of the mandrel 1 inside the resin outlet 6 of the die 5 which communicates with the resin passage 3 along the resin outlet 6. Inflation molding is performed using a die equipped with an annular cooling medium passage 7. Note that the annular shape herein includes not only a perfect circular ring shape but also an elliptical ring shape with various oblateness. In this case, the cooling medium passage 7 has a resin discharge port 6 which has almost the same surface as the outer surface of the outer die ring 2 located outside the resin discharge port 6 (actually, the resin discharge port is recessed within a range of 1 mm or less). ) is formed near the outer surface of the mandrel 1. This coolant passage 7 communicates with a coolant inlet 8 and a coolant outlet 9 . Further, the cooling medium passage 7 needs to be formed along the resin discharge port 6, and may have a spiral shape toward the center, a spiral shape two or three times along the resin passage 3, or other shapes. There is no problem in forming it. There are various ways to form the cooling medium passage 7, but for example, a groove of a predetermined shape is bored in the mandrel 1, the lid 10 is placed over the groove, and the groove is welded or bolted ( (not shown) or the like. In this case, the distance between the upper end of the cooling medium passage 7 and the outer surface of the mandrel 1 is within 30 mm, preferably within 20 mm, and most preferably within 15 mm. FIG. 2 shows another embodiment of the die used in the method of the present invention. In a die 5 similar to that in FIG. 1, the outer surface of the mandrel 1, which is inside the resin discharge port, The cooling medium passage 7 is formed in this protrusion 11 . In this figure, the same reference numerals as in FIG. 1 represent the same members. FIG. 3 shows still another embodiment of the die used in the method of the present invention, in which the outer surface of the mandrel 1 is connected to the outer die ring 2 as in FIG.
The cooling medium passage 7 is formed at a position of the protruding portion 11 on the same plane as the outer surface of the outer die ring 2 . in this case,
The cooling medium passage 7 can be formed by various methods, but for example, as shown in FIG. It can be formed by placing an annular lid having a groove thereon so that the shapes of both grooves match and fixing with bolts (not shown) or the like. In this figure, the same reference numerals as in FIG. 1 represent the same members. FIG. 4 shows another embodiment of the die used in the method of the present invention, in which the outer surface of the mandrel 1 protrudes from the outer surface of the outer die ring 2, similar to FIG. 11 and the mandrel 1, a spiral cooling medium passage 7 is formed. In this figure, the same reference numerals as in FIG. 1 represent the same members. Figures 5 and 6 show yet another embodiment of the die used in the method of the present invention.
In the die similar to the figure, a spiral cooling medium passage 7 is formed near the outer surface of the mandrel 1. In this figure, the same reference numerals as in FIG. 1 represent the same members. In order to carry out inflation molding of thermoplastic resin using such a die, the molten thermoplastic resin is passed through the resin passage 3, while the cooling medium is introduced into the cooling medium passage 7 from the cooling medium inlet 8. By introducing and circulating the resin, the molten thermoplastic resin is annularly discharged from the resin discharge port 6 while cooling only the outer surface of the mandrel inside the resin discharge port.
Before the annular (cylindrical) thermoplastic resin thus discharged is solidified, air is replenished through the air outlet 4 to retain air inside the annular resin. Here, to retain air means to introduce a predetermined amount of air into the annular resin so that the resin immediately after exiting the discharge port is crushed so that the inner surfaces do not come into contact with each other. That is, according to the present invention, the thermoplastic resin in a molten state is not substantially cooled in the resin passage, and only the portion corresponding to the inner surface is rapidly cooled immediately before being discharged from the resin discharge port, so that only the inner surface is cooled during discharge. It is thought that turbulence occurs in the process, forming a rough surface with uniform fine irregularities. In this case, within 30 mm, preferably within 20 mm, in the axial direction from the lower end of the resin discharge port, especially
Particularly excellent effects can be obtained by lowering the cooling temperature of the inner surface within 15 mm by 5 to 60° C., preferably by 10 to 50° C., and most preferably by 15 to 35° C., relative to the external temperature. For example, in the case of soft vinyl chloride resin, the temperature of the outer die ring 2 is set to 150 to 200°C, the temperature of the mandrel tip is set to 120 to 160°C, and only the inner surface is cooled and discharged, so that the outer surface has a mirror surface. Moreover, a cylindrical film having a rough inner surface with uniform fine irregularities can be obtained. However, if the temperature difference between the two sides of the die is less than 5°C, a sufficiently rough surface will not be formed, while if it exceeds 60°C, the resin temperature will drop too much, causing turbulent flow throughout the resin, making it difficult to obtain a uniform sheet. That's because there isn't. Note that the cooling medium passage is not limited to those shown in FIGS. 1 to 6, and may have any structure as long as it cools only the resin discharge port of the mandrel. For example, it may have a double or triple spiral shape. When such a spiral shape is used, it is preferable to install the cooling medium so that it moves from the inside of the mandrel toward the resin discharge port.
This can increase the uniformity of the temperature at the resin discharge port. The most suitable thermoplastic resin to be molded by the method of the present invention is soft vinyl chloride resin, but it is not limited to this, and any resin whose flow characteristics are similar to those of the soft vinyl chloride resin can be used. Examples of such thermoplastic resins include ethylene-vinyl acetate copolymer, polypropylene,
Examples include olefin thermoplastic elastomer and chlorinated polyethylene. Cooling media include silicone oil, air, and the like. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Using a die shown in FIG. 1 in which the lower end of the cooling medium passage 7 was positioned 10 mm from the tip of the mandrel 1, a soft vinyl chloride resin [vinyl chloride resin (degree of polymerization 1300) 100 G-2- in weight part
50 parts by weight of ethylhexyl phthalate (DOP),
Contains 3 parts by weight of epoxidized soybean oil, 0.5 parts by weight of Zn-Ca metal soap stabilizer, and 0.5 parts by weight of lubricant]
molten material (160°C) is flowed through the resin passage, discharged into the air from the resin discharge port 6, and the air discharged from the air discharge port 4 is retained inside the resin passage to increase the thickness.
A cylindrical film with a diameter of 0.4 mm and a folded diameter of 180 mm was obtained. During this time, compressed air, which is a cooling medium, is introduced at high speed into the cooling medium passage 7 through the cooling medium inlet 8, and while cooling only the resin discharge port of the mandrel 1 to 135°C, it is discharged from the system through the cooling medium discharge port 9. I let it happen. The obtained film had a rough surface having uniform fine irregularities on the inner surface. This film was cut to a length of 300 mm, and predetermined positions were sealed with high frequency to obtain a bag-shaped medical device. The blocking state of the inner surface of the obtained bag-shaped medical device was examined. The results are shown in Table 1. The observed blocking states were classified based on the following criteria. Blocking after autoclave sterilization was also examined in the same manner. 0: There is no blocking at all, and the mouth can be opened naturally by holding one end of the sheet. 1: There are some blocked areas, but the mouth can be opened easily. 2: There are some blocked areas and it is difficult to open the mouth. 3: It is difficult to open the mouth due to blocking on the entire surface, but if you open the mouth, the inner blocking will come off naturally. 4: Blocking occurs on the entire surface, making it difficult to open the mouth, and even if the mouth is opened, the inner blocking remains as it is. In addition, in order to determine the transparency of the obtained bag-shaped medical devices, the absorbance (log I ₀ /I) at 700 to 400 nm was measured for empty medical devices and medical devices filled with water.
was measured. The spectral absorbance difference between 700 and 400 nm was less than 0.05 for all samples, and there was no dependence on wavelength. The results are shown in Table 1. The degree of transparency based on absorbance is as follows. 1.0< white opaque 0.5~1.0 white translucent <0.5 colorless and transparent Example 2 The lower end of the cooling medium passage 7 is positioned 10 mm from the tip of the annular protrusion 11 at the tip of the mandrel 1 as shown in FIG. Inflation molding was performed in the same manner as in Example 1 using the die shown, except that silicone oil (Toshiba silicone oil TSF451) was used as a cooling solvent (temperature of the resin outlet inside the die was 130°C). When I got old,
A film was obtained in which a rough surface having uniform fine irregularities was formed on the inner surface. Example 1 with this film
A medical device was made in the same manner as above, and the blocking state was examined in the same manner, and the results were as shown in Table 1. Examples 3 to 4 Inflation molding was performed in the same manner as in Example 1, except that the die shown in Fig. 4 was used (resin outlet temperature inside the die was 135°C). A film with a rough surface having uniform fine irregularities was obtained. A medical device was made from this film in the same manner as in Example 1, and the blocking state was examined in the same manner as shown in Table 1. Comparative Example 1 As shown in Fig. 7, the cooling medium passage is formed in a spiral shape to cool almost uniformly the entire circumferential surface of the mandrel in the axial direction.
Inflation molding was performed in the same manner as in Example 1, except that the die described in No. A film with no formation was obtained. A medical device was made from this film in the same manner as in Example 1, and the blocking state was examined in the same manner as shown in Table 1.

[Table] Comparative Example 2 When the same die as Comparative Example 1 was used and the same silicone oil cooling was performed as in Example 2, the entire resin became large bellows-like unevenness, and the strength of the molten resin coming out from the discharge port was It was impossible to carry out inflation molding because the material was weak and could not be removed. V. Specific Effects of the Invention As described above, the present invention has an annular resin passage formed by a mandrel and an outer die ring surrounding the mandrel. and the temperature of at least the surface facing the resin passage of the mandrel not exceeding 30 mm in the axial direction from the lower end of the resin discharge port of the die communicating with the resin passage is lower than the temperature of the surface of the outer die ring facing the resin passage. The molten thermoplastic resin is discharged in a ring shape from the resin discharge port at a temperature of 5 to 60 degrees Celsius, and air is retained inside the discharged resin to form a ring-shaped thermoplastic resin film. This is a method for manufacturing an annular thermoplastic resin film with a roughened inner surface, which is characterized by forming a roughened surface with uniform fine irregularities on the inner surface, so that formation is not possible using conventional inflation molding methods. There is an advantage that a rough surface having uniform fine irregularities can be easily formed on the inner surface. In addition, since the film obtained by the method of the present invention has a rough surface with uniform fine irregularities on the inner surface, blocking will not occur even if the inner surfaces are brought into contact with each other, and even if the inner surfaces are brought together and brought into contact. It has the advantage of being extremely transparent when liquid is stored in the prepared container. Therefore, the film formed by the method of the present invention is extremely useful as a film for forming medical devices such as blood bags, transfusion bags, dialysate bags, urine storage bags, and the like. Further, the present invention provides a die comprising a mandrel, an outer die ring surrounding the mandrel, an annular resin passage formed between the mandrel and the outer die ring, and a resin discharge port communicating with the resin passage. A cooling means for making the temperature of at least the surface of the mandrel of the die facing the resin passage lower than the temperature of the surface of the outer die ring facing the resin passage. This is an apparatus for manufacturing an annular thermoplastic resin film with a roughened inner surface, characterized in that the resin discharge port is provided in a portion of the mandrel not exceeding 30 mm in the axial direction from the resin discharge port to the resin passage side. Only the inner side of the molten resin discharged from the discharge port can be rapidly cooled, and therefore a rough surface having uniform fine irregularities is formed only on the inner surface due to surface contraction of the resin.

[Brief explanation of drawings]

1 to 5 are cross-sectional views schematically showing a die for carrying out the method of the present invention, and FIG. 6 is a cross-sectional view of the die shown in FIG.
7 is a sectional view taken along the line, and FIG. 7 is a sectional view schematically showing a die used in a conventional inflation molding method. 1...Mandrel, 2...Outer die ring, 3
... Resin passage, 4 ... Air discharge port, 5 ... Die,
6...Resin discharge port, 7...Cooling medium passage, 8...
Cooling medium inlet, 9...Cooling medium outlet.

Claims (1)

[Scope of Claims] 1. A die comprising a mandrel and an outer die ring surrounding the mandrel, and having an annular resin passage, in which a molten thermoplastic resin flows into the resin passage, and a die that communicates with the resin passage. The temperature of at least the surface of the mandrel facing the resin passage not exceeding 30 mm in the axial direction from the lower end of the resin discharge port of the die is 5 to 60°C lower than the temperature of the surface of the outer die ring facing the resin passage. The molten thermoplastic resin is discharged in an annular shape from the resin discharge port, and air is retained inside the discharged resin to form an annular thermoplastic resin film, and the inner surface of the film has uniform fine irregularities. A method for producing an annular thermoplastic resin film having a roughened inner surface, characterized by forming a roughened surface. 2 The temperature difference between the mandrel and the outer die ring is 10
The manufacturing method according to claim 1, wherein the temperature is 50°C. 3 Temperature difference between mandrel and outer die ring is 15~
The manufacturing method according to claim 2, wherein the temperature is 35°C. 4. An annular thermoplastic having a die consisting of a mandrel, an outer die ring surrounding the mandrel, an annular resin passage formed between the mandrel and the outer die ring, and a resin discharge port communicating with the resin passage. In a resin film manufacturing apparatus, a cooling means is provided at the resin discharge port for making the temperature of at least the surface of the mandrel of the die facing the resin passage lower than the temperature of the surface of the outer die ring facing the resin passage. 30 in the axial direction from to the resin passage side
An apparatus for manufacturing an annular thermoplastic resin film with a roughened inner surface, characterized in that it is provided on a portion of a mandrel not exceeding mm. 5. The manufacturing apparatus according to claim 4, wherein the cooling means circulates a cooling medium through a cooling medium passage formed in an annular shape at least near the outer surface of the mandrel along the resin discharge port. . 6. The manufacturing apparatus according to claim 5, wherein the cooling medium passage is formed near the outer surface of the mandrel, which has the same surface as the outer surface of the resin discharge port. 7. The manufacturing apparatus according to claim 5, wherein the cooling medium passage is formed near the surface of the mandrel that protrudes from the outer surface of the resin discharge port. 8. The manufacturing apparatus according to claim 5, wherein the cooling medium passage is formed within a mandrel protruding from the outer surface of the resin discharge port and at a position substantially flush with the outer surface of the outer die ring. .